There are four integral modules in a Cyber-Physical Networking System (CPNS): sensing, communication, decision, actuating. Among them, the communication module plays the vital role of central liaison. It glues everything together and orchestrates the operation of the whole system. Nowadays, local communications are not enough for practical CPNSs which can be very large in geographical scale. Such CPNSs require reliable and fast communication channels over a long distance. The 3G cellular networks provide a convenient and mature way. However, as different standards compete for dominance in the 3G market, it is necessary for us to gain a thorough understanding of the empirical performance for each of the standards. In this paper, we have conducted a large-scale empirical field study on 3G mobile systems performance in China. From the results, we have confirmed that the performance of 3G is largely satisfactory, especially in indoor environments and for high rate data services. On the other hand, we have made some unexpected new findings, which are helpful to improve the 3G system, especially the TD-SCDMA networks, to better serve the needs of practical large CPNSs.